High Prevalence of Streptococcus pneumoniae with Mutations in pbp1a, pbp2x, and pbp2b Genes of Penicillin-Binding Proteins in the Nasopharynx in Children in Japan

Nosocomial Pneumonia in Georgia: A Focus on Gram-Positive Bacteria and Antimicrobial Resistance

Nosocomial pneumonia represents a significant clinical challenge worldwide, and in Georgia, the burden of this healthcare-associated infection is a growing concern. This study investigates the role of gram-positive bacteria in nosocomial pneumonia cases, focusing on their prevalence, antimicrobial resistance patterns, and associated risk factors. A retrospective analysis of 484 clinical samples collected from 397 patients between May 2022 and September 2024 highlights the distribution of pathogens, with a particular emphasis on Staphylococcus aureus and Streptococcus pneumoniae. Among gram-positive pathogens, Staphylococcus aureus was the most prevalent, accounting for 103 cases (21.3%), followed by Streptococcus pneumoniae with 45 cases (9.3%). The study identifies alarming rates of antimicrobial resistance among gram-positive pathogens. Staphylococcus aureus isolates demonstrated universal penicillinase production (103/103, 100%) and high levels of mecA-mediated methicillin resistance (89/103, 86.4%) and erm-mediated macrolide resistance (74/103, 71.8%). Additionally, notable resistance was observed to tetracycline (93/103, 90.3%), aminoglycosides (31/103, 30.1%), and fluoroquinolones (41/103, 39.8%). Streptococcus pneumoniae isolates exhibited universal penicillinase production (45/45, 100%), with complete beta-lactam resistance found in 42 isolates (42/45, 93.3%), mediated through mutations in the pbp1a, pbp2x, and pbp2b genes. Furthermore, erm(B)-mediated macrolide resistance was observed in 37 isolates (37/45, 82.2%), tetM-mediated tetracycline resistance in 37 isolates (37/45, 82.2%), and fluoroquinolone resistance in 13 isolates (13/45, 28.9%). One isolate of each pathogen demonstrated vancomycin resistance, underscoring the emergence of multidrug-resistant (MDR) strains. The study underscores the need for stringent infection control measures and rational antibiotic stewardship to mitigate the impact of resistant gram-positive pathogens in Georgian healthcare settings. The findings also stress the importance of continuous surveillance to monitor resistance trends and guide empirical therapy. By exploring the resistance mechanisms and prevalence of gram-positive bacteria in nosocomial pneumonia, this research contributes to a deeper understanding of the local epidemiology and highlights actionable insights for improving patient outcomes.

Ten-Year Trends and Clinical Relevance of the Antimicrobial Resistance Genotype in Respiratory Isolates of Streptococcus pneumoniae

Background: Antimicrobial resistance of Streptococcus pneumoniae, especially against β-lactam antibiotics, is a global concern. We aimed to analyze a 10-year trend in the antimicrobial resistance genotype of respiratory isolates of S. pneumoniae and to clarify whether resistance genotypes were correlated with phenotypic drug susceptibility, pathogenicity, and host clinical background. Methods: Respiratory isolates of S. pneumoniae from 2003 to 2012 were analyzed with polymerase chain reaction for the presence of β-lactam resistance gene mutations on pbp1a, pbp2x, and pbp2b. Sixty-eight strains isolated from different patients in 2012 were particularly analyzed for the association between genotypes and clinical data. Results: The 10-year trend analysis showed a recent increase in gPRSP (genotypic penicillin-resistant S. pneumoniae) with all 3 β-lactam resistance genes (from 21.7 to 35.3% in 3 years) and a steady level of gPSSP (genotypic penicillin-susceptible S. pneumoniae) without any β-lactam resistance genes (13.2% in 2012). This resistance trend in genotypes was more prominent than resistance phenotypes determined with a drug susceptibility test. The probability of being a causative pathogen did not differ in gPSSP (55.6%), gPISP (genotypic penicillin-intermediate resistant S. pneumoniae; 54.3%), and gPRSP (54.2%). There was no significant difference in the ratio of patients who presented with respiratory failure in respiratory infection caused by gPSSP, gPISP, or gPRSP. Host clinical characteristics including age and gender were not different among resistance genotypes. Conclusions: There was no difference in pathogenicity or clinical background between gPSSP, gPISP, and gPRSP. Antimicrobial resistance in respiratory isolates of S. pneumoniae was more prevalent in genotypes than in phenotypes.

Molecular epidemiology of nonencapsulated Streptococcus pneumoniae among Japanese children with acute otitis media

The introduction of pneumococcal conjugate vaccine may change the epidemiology of Streptococcus pneumoniae. The increased prevalence of non-vaccine serotypes as the cause of pneumococcal diseases has already reported in the United States and Europe. However, little attention has been focused on the S. pneumoniae. In this study, nonencapsulated S. pneumoniae were identified in 15 isolates (6.4%) out of 236 pneumococcal strains obtained from the nasopharynges of children with acute otitis media (AOM), in 3 isolates (14.3%) out of 21 strains from acute rhinosinusitis, and in 2 isolates (12.5%) out of 16 nasopharyngeal carriage strains obtained from normal healthy children. Among the 20 nonencapsulated S. pneumoniae isolates, 15 (75.0%) isolates had the pspK gene. Seven sequence types (STs) were identified: ST7502 (5 strains), ST1106 (2 strains), ST7803 (2 strains), ST7786 (1 strain), ST6741 (1 strain), ST7496 (1 strain), and ST8642 (1 strain). Because nonencapsulated S. pneumoniae strains are not targeted by the current available pneumococcal vaccines, these strains will gradually become more common in nasopharyngeal carriage. The increase in colonization and dissemination of these strains would increase the risk of AOM and other systemic pneumococcal diseases against which current vaccines cannot provide protection. Nonencapsulated S. pneumoniae may thus become more prevalent as human pathogen.

Genetic characteristics of Haemophilus influenzae and Streptococcus pneumoniae isolated from children with conjunctivitis-otitis media syndrome

Acute conjunctivitis is the most common ocular disorders among children and frequently concomitant with acute otitis media (AOM) as conjunctivitis-otitis syndrome. In this study, we evaluated prevalence of causative pathogens and PCR-based genotypes of Haemophilus influenzae and Streptococcus pneumoniae among children with conjunctivitis-otitis media syndrome. Nontypeable H. influenzae (NTHi) is identified most often at 61.8% in conjunctiva exudates followed by S. pneumoniae at 28.2% and Moraxella catarrhalis at 19.1%. Genetic β-lactamase nonproducing ampicillin resistant (gBLNAR) strains of NTHi and genetic penicillin resistant S. pneumoniae (gPRSP) were identified at 72.1% and at 74.2% among conjunctiva isolates by polymerase chain reaction (PCR), respectively. Pneumococcal strains having either ermB or mefE genes were identified at 93.5% among conjunctiva isolates. The restriction fragment of patterns of 89.7% pairs of H. influenzae isolates and 100% pairs of pneumococcal isolates from conjunctiva exudates, middle ear fluids (MEFs) and nasopharyngeal swabs were identical. In contrast to the previous reports, most prevalent strains from conjunctivitis-otitis media syndrome was BLNAR H. influenzae in this study. The causative pathogen responsible for acute conjunctivitis will be originated from the nasopharynx. In the absence of MEFs one can possibly rely on the nasopharyngeal culture to guide an appropriate treatment.

PspA family distribution, antimicrobial resistance and serotype of Streptococcus pneumoniae isolated from upper respiratory tract infections in Japan

Background

The protection against pneumococcal infections provided by currently available pneumococcal polysaccharide conjugate vaccines are restricted to the limited number of the serotypes included in the vaccine. In the present study, we evaluated the distribution of the pneumococcal capsular type and surface protein A (PspA) family of pneumococcal isolates from upper respiratory tract infections in Japan.

Methods

A total of 251 S. pneumoniae isolates from patients seeking treatment for upper respiratory tract infections were characterized for PspA family, antibiotic resistance and capsular type.

Results

Among the 251 pneumococci studied, the majority (49.4%) was identified as belonging to PspA family 2, while most of the remaining isolates (44.6%) belonged to family 1. There were no significant differences between the distributions of PspA1 versus PspA2 isolates based on the age or gender of the patient, source of the isolates or the isolates’ susceptibilities to penicillin G. In contrast, the frequency of the mefA gene presence and of serotypes 15B and 19F were statistically more common among PspA2 strains.

Conclusion

The vast majority of pneumococci isolated from the middle ear fluids, nasal discharges/sinus aspirates or pharyngeal secretions represented PspA families 1 and 2. Capsular serotypes were generally not exclusively associated with certain PspA families, although some capsular types showed a much higher proportion of either PspA1 or PspA2. A PspA-containing vaccine would potentially provide high coverage against pneumococcal infectious diseases because it would be cross-protective versus invasive disease with the majority of pneumococci infecting children and adults.

Serotype distribution and penicillin resistance of Streptococcus pneumoniae isolates from middle ear fluids of pediatric patients with acute otitis media in Japan

Out of 175 pneumococcal isolates from middle ear fluids, 26.3% were penicillin-resistant S. pneumoniae (PRSP). Serotypes 19F and 23F occurred most frequently among PRSP strains. The 7-valent pneumococcal conjugate vaccine (PCV) showed better coverage of PRSP strains (87.0%). The 7-valent PCV may reduce the prevalence of PRSP in Japan.

Determination of pneumococcal serotypes/genotypes in nasopharyngeal secretions of otitis media children by multiplex PCR

The appropriate clinical applications of pneumococcal polysaccharide vaccines against recent increases in antimicrobial resistant Streptococcus pneumoniae (S. pneumoniae) urgently require accurate analytical methodologies for determining and characterizing the serotypes. The results of current immunological determinations of serotypes with anti-capsular polysaccharide-specific sera are difficult to interpret in terms of quellung changes of the pneumococci. In this study, we applied the multiplex PCR technique for the rapid identification of pneumococci and simultaneous rapid determinations of their serotypes and genotypes that directly correlated with antimicrobial susceptibilities from nasopharyngeal secretions (NPS). Serogroups 6, 19F and 23F were the predominant capsular types of S. pnuemoniae in the NPS samples. Strains of serotypes 19F and 23F frequently had mutations in pbp1a, pbp2x and pbp2b and expressed ermB and mefA; they also were mostly resistant to both penicillin G (PCG) and clarithromycin (CAM). Two NPS samples contained the strain of serotype 19F together with the strain of serotype 23F, although only the strain of serotype 19F was identified by a conventional bacterial culture. Pneumococci were identified in six NPS samples and their serotypes determined by the multiplex PCR, while a conventional bacterial culture failed to identify the pathogens. Our findings suggest that PCR-based serotyping and genotyping can provide an accurate and rapid distribution of pneumococcal serotypes and antimicrobial resistance. The relatively minor populations in the nasopharynx may be determined using molecular techniques.

Meta-analysis of antibiotic susceptibility and the genotype of penicillin-binding proteins in Streptococcus pneumoniae

To further understanding of the mechanisms of development of resistance to penicillin in Streptococcus pneumoniae, and the role of penicillin-binding proteins (PBPs) mutations to antibiotics resistance a meta-analysis was performed. Major databases, Pubmed, Current Contents, Biosis previews, Web of Science, were searched for studies that published within 1997 through to 2007, and reported the penicillin MIC and the alteration of PBP 1a, 2b and 2x (genes or proteins) of clinical S. pneumoniae isolates. Papers were reviewed by 2 persons and used standard criteria to enroll them. Meta-analysis was performed using a random-effects model. Overall, 20 studies were included in the meta-analysis. For the included 1771 clinical S. pneumoniae isolates, the susceptibility to penicillin decreased in inverse proportion to the presence of mutated pbp genes. The mutations of the conserved amino acid motifs STMK and SRNVP of PBP 1A, STMK and LKSG of PBP2X, and SSNT of PBP2B are critical for the penicillin resistance. Those motifs can be used as markers for the penicillin susceptibility of S. pneumoniae. These results are useful in helping define the mechanism of penicillin resistance in S. pneumoniae.

Efficacy of a novel oral carbapenem, tebipenem pivoxil (TBM-PI), against experimental otitis media caused by penicillin resistant Streptococcus pneumoniae in chinchilla

An animal model of otitis media using chinchillas was developed to evaluate the efficacy of tebipenem pivoxil (TBM-PI) against experimental otitis media. Chinchillas inoculated via the transbullar approach with Streptococcus pneumoniae serogroup 6 were included in the efficacy study with TBM-PI, amoxicillin (AMX) or untreated as controls. TBM-PI resulted in survival rate of 83%, compared with 25% survival for AMX and 0% survival for controls (p<0.01). Quantitative cultures in the middle ear effusions at day 5 of the TBM-PI group yielded 3.5+/-2.4log(10)CFUs/ml. TBM-PI is a promising antibiotic for the treatment of acute otitis media.